Dennis G
05-04-2007, 06:01 PM
Focal reducer
The magnification of the imager Toucam is such that it only photographs a segment of the moon. Wanting to photograph the whole moon and having read where one can reduce the magnification using a focal reducer, I contacted a Sydney firm requesting information while providing the telescope specifications and was told I could purchase a reducer that would provide .7 and .5 reduction, which would allow the whole moon to be photographed.
I received a single lens, marked 1.25 Focal Reducer, similar to a 1.25 filter, with a note to say the remaining section (what ever?) to follow when stocks arrive.
Screwed to the Toucam I found I could not focus the imager. The moon could be vaguely seen on the computer screen, but I couldn’t rack the device, further IN, it being at the limit of the focuser.
I made a temporary plastic 1.25 mm adaptor, which provided a further reduction of about 10 mm, but to no avail. I made an adjustable tube; about 50 mm long, which received the reducer lens and the tube screwed to the imager. Not knowing how long this should be it failed to come to focus. Is there some kind person who could advise me what I need to do to bring this device in focus, or am I expecting the impossible?
Telescope specification
Dob, 205mm , F5 mirror. The information below, so kindly supplied, convinced me to purchase the reducer:
Quote: The Reducer will reduce your focal length by either .7 or .5 That means that your focal length will go from (8" f/5) 1016mm to 711mm (.7) or 508mm (.5) resulting in wide field of vie and therefore you would be able to fit the whole disk of the moon in.
Great if I could focus the device! Or is the secret in the remaining section not supplied? I’m new at the game, old, but not too old to accept advice!
Dennis G:help:
The magnification of the imager Toucam is such that it only photographs a segment of the moon. Wanting to photograph the whole moon and having read where one can reduce the magnification using a focal reducer, I contacted a Sydney firm requesting information while providing the telescope specifications and was told I could purchase a reducer that would provide .7 and .5 reduction, which would allow the whole moon to be photographed.
I received a single lens, marked 1.25 Focal Reducer, similar to a 1.25 filter, with a note to say the remaining section (what ever?) to follow when stocks arrive.
Screwed to the Toucam I found I could not focus the imager. The moon could be vaguely seen on the computer screen, but I couldn’t rack the device, further IN, it being at the limit of the focuser.
I made a temporary plastic 1.25 mm adaptor, which provided a further reduction of about 10 mm, but to no avail. I made an adjustable tube; about 50 mm long, which received the reducer lens and the tube screwed to the imager. Not knowing how long this should be it failed to come to focus. Is there some kind person who could advise me what I need to do to bring this device in focus, or am I expecting the impossible?
Telescope specification
Dob, 205mm , F5 mirror. The information below, so kindly supplied, convinced me to purchase the reducer:
Quote: The Reducer will reduce your focal length by either .7 or .5 That means that your focal length will go from (8" f/5) 1016mm to 711mm (.7) or 508mm (.5) resulting in wide field of vie and therefore you would be able to fit the whole disk of the moon in.
Great if I could focus the device! Or is the secret in the remaining section not supplied? I’m new at the game, old, but not too old to accept advice!
Dennis G:help: